Coil winding for electric apparatus and method of making same



A. T. SINKS Aug. 6, 1946.

COIL WINDING FOR ELECTRIC APPARATUS AND METHOD OF MAKING SAME Filed0c'b..25, 1943 Inventor-z Allen "IT Sinks,

H15 1 Attor ney.

Patented Aug. 6, 1946 COIL WINDING FOR ELECTRIC APPARATUS AND METHOD OFMAKING SAME Allen T. Sinks, Beach Blufi, Mass, assignor to GeneralElectric Company, a corporation of New York Application October 23,1943, Serial No. 507,419

8 Claims.

My invention relates to a coil winding for an electrical inductionapparatus and to a method of forming the coil winding.

Heretofore it has been customary to form some types of electricalinduction apparatus such as instrument current transformers with atunnel type porcelain body which includes a tubular shaped inner walland a spaced outer wall forming a winding space. The outer Wall usuallyextends into a relatively long tubular member on the top of which ismounted the terminals of the transformer. Inside the winding space andbetween the spaced wall members there is provided a few turns of wire toform the primary winding of the transformer. Through the tunnel on theoutside of the porcelain is placed the core winding leg and the lowvoltage secondary winding. It will be understood that the space betweenthe porcelain walls inside the pot type porcelain is relatively narrowand some difliculty has been experienced in the past in winding theconductor around the inner porcelain body to provide the high voltagewinding. This has usually been accomplished by taking an insulatedconductor and working it around the inner body a suflicient number oftimes to form a plurality of turns so as to produce the high voltagewinding. However, such prior methods have been susceptible of crackingor injuring the relatively hard surface of the porcelain and such priormethods are usually rather tedious and expensive.

It is therefore an object of my invention to provide an improved highVoltage primary winding for a pot type current transformer of the abovementioned type.

A further object of my invention is to provide an electric inductionapparatus with an improved coil winding which is simple in constructionand eflicient in operation.

A still further object of my invention is to provide an improved methodfor facilitating the forming of a high voltage Winding around a tubularbody in the cavity of a pot type insulated transformer.

Further objects and advantages of my invention will become apparent fromthe following description referring to the accompanying drawing, and thefeatures of novelty which characterize my invention will be pointed outwith particularity in the claims annexed to and forming a part of thisspecification.

In the drawing Fig. l is a side elevation in partial sectionillustrating a pot type instrument transformer which is provided with anembodiment of my invention; Fig. 2 is a perspective view of the pot typeinsulator employed in the construction of Fig. 1; Fig. 3 illustrates myimproved method of winding the high voltage winding of the transformerillustrated in Fig. 1; and Fig. 4 is an exploded perspective view of aportion of the high voltage Winding employed in the construction of Fig.1.

Referring more particularly to Fig. 1 of the drawing, I have illustratedan electrical induction apparatus which has particular application as ahigh voltage instrument current transformer which includes a pot typeinsulator II) having a cavity II, at the bottom of which there isprovided a tubular shaped wall I2 and a spaced bottom wall I3 providinga winding space I l. The tubular shaped wall I2 is hollow so as toprovide an opening or tunnel I5 through which extends a winding leg I6of a core in the conventional manner. The core is formed in two halveswith an outer yoke portion I! which connects with half of the windingleg I 6. The other half of the winding leg I6, it will be understood,connects with a yoke similar to I! and on the opposite side of thetransformer. A base member I8 of suitable metallic material is providedwhich surrounds the core members and which supports the pot typeinsulator through a metallic flange member I9 which is in turn attachedto the insulator in any suitable manner such as by cementing, as isindicated at 20. The top of the cavity I I is closed through a covermember 21 which is attached to the top of the insulator through a collar22 which is in turn supported by a shoulder 23 of the insulator and iscemented, as is illustrated by the numeral 24. A pair of terminals 25and 26 are provided on the cover which in turn connect to the highvoltage primary winding, the construction of which will be describedbelow. Low voltage terminals 21 are provided which are supported by thebase I8 which are connected to a low voltage winding 28 through aconductor 29. The low voltage winding 28 surrounds the winding leg andis inside the tunnel I5.

In order to provide an improved high voltage winding arrangement, Iprovide a spool member 30 which is split and which is formed of twosemicylindrical portions 3I and 32, as will be seen in detail in theexploded View of Fig. 4. These members may be made of any suitablematerial and are formed of conducting material such as copper for thereasons which will be apparent as the following description proceeds.The semi-cylindrical members 3| and 32 are placed around the tubularinner wall I2, as is illustrated in Figs. 1

e) and 3, with the abutting surfaces 33 slightly spaced and the surfacesas abutting. Suitable dowel pins which extend into holes 36 may beprovided fOr properly positioning the semi-cylindrical members. In orderthat the spool will not provide a short-circuited turn around theWinding legs, the split spool is provided with a' longitudinal or axialdiscontinuity in the form of an insulating member 37 which is placedbetween the adjacent surfaces at 33.

In order to provide a convenient arrangement for winding a conductoraround the spool to provide the high voltage winding, each of thesemicylindrical portions 3! and 32 forming the spool is provided withspaced flanges 38 and 39 which have gear teeth it formed about the outerperiphery thereof. Any suitable conducting material may be provided forthe high voltage winding and in the construction illustrated it will beI seen that the high voltage conductor is in the form of a relativelywide and thin copper strip 4| which is wound off a suitable spool of thematerial 42. An end of the copper conductor 4| is attached to the spoolin any suitable manner, such as by welding, as is indicated by thenumeral 43. This connection may be made between the conduotor and themember 3! before the semi-cylindrical members are inserted in theporcelain. Also, as soon as one turn of the conductor is wound on thesplit spool, the semi-cylindrical members will be held together by theconductor. As the spool is wound up, interturn insulation may beprovided between the turns of the conduotor by a suitable sheet ofinsulating material 14 which is wound off a spool 45.

In order to rotate the spool around the inner wall !2, I provide chainmembers 46 which mesh with the sprockets or teeth ii! on the peripheralflanges of the spool. It will be understood that a pair of continuouschains may be employed which mesh with each of the sprockets it, onlyone of which, however, is shown in Fig. 3. It is also to be understoodthat chains cooperate with suitable tooth wheels 55 which may be rotatedby a suitable source of power (not shown) so as to rotate the spool.Thus by rotating the spool the copper conductor 4! with its insulation44 will be wound around the tubular portions of the semicylindricalmembers 3! and 32, thus providing a continuous coil of concentricconvolutions. It is to be understood that the spool is sufiicientlylarge so as to be able to rotate around the outer surface of the wall l2and, to indicate this, there is shown a slight clearance between thewall l2 and spool 39.

In order to minimize binding between the inner surface of the spool andthe outer surface of the wall 92, I provide a thrust member 59 whichincludes a rod having a pair of rollers 59 and 52 which roll on theouter surface of the spool and on the convolutions of the conductor asthe con duotor is wound around the spool. Thus as the chain is rotatedto produce a torque which in turn rotates the spool, the spool will tendto be forced upwardly against the bottom surface of the wall E2. Suchrubbing, however, might tends to crack or injure the porcelain and inorder to prevent this, the thrust member 563 with the rollers isprovided which pushes downwardly with a force which may be madesubstantially equal to the upward force of the chain, thus allowing thespool to rotate relatively freely around the outer surface of the wallmember Hi. This force is accomplished through a spring member 52' whichis inside a tubular member 53 into which an end 4 of the rod 50 extends.The topsuriace of the tubular member 53 may be supported in any suitablemanner, such as through a base 66 which in turn supports the rotatablewheels 65 which in turn cause the chains 46 to rotate.

My improved method of forming the high voltage winding around thetubular wall 12 at the bottom of the cavity of a pot type insulator,therefore, includes the steps of surrounding the tubular wall with thesplit spool with the conductor attached. The chain is then assembled forrotating the spool. A suitable amount of thrust is thereby providedthrough the thrust member 59 so that when the spool is rotated it willmove relatively freely around the outer surface of the wall i2. After asuitable number of turns have been placed on the spool, the conductormay be cut and an end 55 attached to a conductor 55 which in turnconnects to the terminal 25 or the conduotor M may continue up to and beattached to the terminal 25.

In order to provide the high voltage winding with another terminal, theterminal 26 is connected to the inner end of the high voltage wind ingthrough the spool. This may be accomplished in any suitable manner suchas by providing a conductor lead 56' which has an inner end brazed. tothe spool. It will be seen, particularly in Fig. 4, that both thesemi-cylindrical members have on each of the flanges relatively flatportions 57 and, in order to facilitate the connection, a strap member53 may be provided which bridges across the flat portions 57!. The strap53 has depending legs 59 of suilicient length, which. is slightly longerthan the thickness of the high voltage winding, so the outerconvolutions will not touch the strap member 58 or are across duringoperation. Taped holes are provided in the flat portions 51, andsuitable screws 50 attach the strap member to the axially spaced flangesof the semicylindrical portions 3!. This strap member pro vides aconvenient place for attaching an end 5! of the conductor 55, as isillustrated in Fig. 1. It will be understood that the screws may beattached to the flat portions 51 by inserting a screw driver in theopening H of the porcelain when the spool is in position with the flatportions 51 facing upwardly. After the strap is assembled. the spool maybe rotated a quarter of a turn so that the leads are attached to thewinding substantially symmetrically. In. order to hold the high voltagewinding snugly in the porcelain after assembly of the winding, asuitable filling compound may be put in the cavity H, as indicated bythe line 62.

Although I have shown and described particular embodiments of myinvention, I do not desire to be limited to the particular embodimentsdescribed, and I intend in the appended claims to cover allmodifications which do not depart from the spirit and scope of myinvention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An electrical induction apparatus including a pot type solid body ofinsulating material havintegral inner tubular shaped wall and anintegral outer wall spaced from said inner wall providing a windingspace between. said walls, a split spool of conducting material loose ysurrounding said inner wall, a conductor wound around said spool withthe inner end attached to said spool, a pair of terminals, and means forconnecting one of said terminals to said spool and the other of theterminals to the outer turn of said wound conductor.

2. An electrical induction apparatus including a solid body ofinsulating material having a tubular inner wall and a spaced outer Wallproviding a winding space, a spool of conducting material surroundingsaid inner wall, a conductor wound around said spool to form a winding,means for connecting the inner end of said conductor to said spool toform one terminal portion for said winding, and means for connecting aconductor to the outer turn of said winding to form another terminal.

3. An electrical induction apparatus including a solid body ofinsulating material having a tubular inner wall and a spaced outer wallproviding a winding space, a split spool of conducting material looselysurrounding said inner wall, a conductor wound around said spool to forma winding, said split spool having an axially extending discontinuity sothat it will not form a shortcircuited turn, one end of said conductorbeing attached to said spool so that said spool forms one terminalportion for the winding.

4. An electrical induction apparatus including a body of insulatingmaterial having a tubular inner wall and a spaced outer wall providing awinding space, a, pair of semi-cylindrical members of conductingmaterial loosely surrounding said inner wall to form a winding spool,means for insulating adjacent surfaces of said members, a conductorwound around said spool to form a winding, said spool having axiallyspaced flanges, means including gear teeth formed about the outerperiphery of said flanges for rotating said spool around said tubularwall for forming said winding.

5. An electrical induction apparatus including a body of insulatingmaterial having a tubular inner wall and a spaced outer wall providing awinding space, a pair of semi-cylindrical members of conducting materialloosely surrounding said inner wall to form a winding spool, means forinsulating adjacent surfaces of said members, a conductor wound aroundsaid spool in layers to form a winding, said spool having axially spacedflanges, means including gear teeth formed about the outer periphery ofsaid flanges for rotating said spool around said tubular Wall forforming said winding, and means for attaching the inner end of saidconductor to said spool.

6. An electrical induction apparatus including a body of insulatingmaterial having a tubular inner wall and a spaced outer wall providing awinding space, a pair of semi-cylindrical members of conducting materialloosely surrounding said inner wall to form a winding spool, a conductorWound around said spool to form a winding, said spool having axiallyspaced flanges, means including gear teeth formed about the outerperiphery of said flanges for rotating said spool around said tubularWall for forming said winding, and means for attaching one end of saidconductor to said spool, a conducting bar bridging said flanges of saidspool, a terminal, and means for connecting said terminal to said bar.

7. A winding for an electrical induction apparatus including a spool ofconducting material, a conductor wound around said spool in layers withthe inner end connected to said spool, means including said spool forproviding one terminal connection for said winding, said spool havingspaced flanges with gear integral teeth on the outer periphery thereofto provide means through which said spool may be rotated to wind on saidconductor.

8. A method of forming a coil winding around a tubular wall at thebottom of the pot type insulated transformer including the steps ofplacing two semi-cylindrical metallic members in the cavity around thetubular wall to form a winding spool, placing a chain in the cavityaround the spool for rotating the spool, rotating the spool, and placinga thrust member in the cavity and against the spool to prevent the spoolfrom binding on the wall during rotation of the spool.

ALLEN T. SINKS.

